Fermentation to produce ethyl alcohol is itself well known, but the existing processes require large amounts of heat and are slow and cumbersome such that, even using complex equipment to maximize efficiency, it is questionable as to whether the energy which can be obtained by combustion of the alcohol product will exceed the energy needed to produce and distill the alcohol. In an application filed Feb. 4, 1980 by one of us, Ser. No. 118,433 a simplified process was described in which a moist finely divided feed containing a component convertible to a fermentable sugar is supplied to a fermentation tank under pressure and at high temperature while most of the water or other liquor to be used in the fermentation process is separately supplied. In this way only the moist feed is heated to the point where conversion to fermentable sugar occurs, and the balance of the fermentation liquor, called the wort, does not have to be heated in practice. The wort is withdrawn continuously or periodically and distilled, and a sizable portion of the heat requirement has to be devoted to vaporizing the beer which is produced when the wort is centrifuged to remove solids therefrom.
This invention relates to apparatus for carrying the process of said prior application in an energyefficient manner.